I’ve had this problem recently. First time was last week when I could load Watopia but not Makuri Islands.
On Monday and Tuesday this week I could Zwift normally (I’d turned my Apple TV off and done a long hold of “home + TV” to reset it, which might have helped), but on Wednesday I couldn’t load any world.
Things were OK again today after updating and the Apple TV being unplugged for a day, but I don’t have a specific way to fix it.